Ion [34], inflammation [28,35], and graft rejection [36] have demonstrated that CCR2-deficient (CCR22/2) mice exhibit enhanced Th2-type responses with increased production of IL-4 and IL-5, but decreased production of IFN-c. Given this bias toward Th2 immunity in the absence of CCR2 signaling, and a potential role for CCR2 in the pathogenesis of psoriasis, we sought to examine whether CCR2-deficient mice are resistant to the development of IL-23-induced psoriasis. To test the hypothesis that CCR2 is required for the development of psoriasis, we injected WT and CCR22/2 mice intradermally with IL-23. We found that the skin of CCR22/2 mice actually becomes more inflamed than that of WT mice, with increased ear swelling and epidermal thickening. Further, instead of psoriasis-like inflammation seen in WT mice, IL-23-induced cutaneous inflammation in CCR22/2 mice buy BIBS39 resembled atopic dermatitis. This inflammation was associated with an increased Th2-type immune response. Although comparable numbers of IL4-secreting CD4+ T cells were present in the draining lymph node and inflamed skin of WT and CCR22/2 mice, increased numbers of eosinophils, mast cells and increased expression of IL-4 and TSLP were detected within IL-23 injected CCR22/2 skin.among total leukocytes. 5 mm sections were stained with toluidine blue for mast cell quantitation. Epidermal thickness was evaluated using NIS-Elements software, and was calculated as: the area of the epidermis/the length of the epidermis.Fluorescence ImmunohistologyFluorescence immunohistology was performed on 10 mm frozen ear skin sections. The sections were air dried for 10 minutes, fixed in 4 paraformaldehyde for 8 minutes, and blocked with PBS containing 5 FBS and 2 mg anti-CD16/CD32 (Biolegend) for 30 minutes at room temperature. Sections were then washed twice in PBS 0.1 Tween and stained overnight with 1 mg of an affinity purified polyclonal antibody to mouse TSLP (R D Systems, BAF555) diluted in PBS 0.1 saponin at 4uC. After washing with PBS 0.1 Tween on ice, sections were stained with 1 mg of AlexaFluor 488-conjugated donkey anti-goat IgG (Invitrogen) for 1 hour at room temperature. After again washing with PBS 0.1 Tween, sections were then stained with 1 mg/mL Hoescht in PBS for 5 minutes. Finally, sections were washed in PBS, mounted with ProLong Gold Antifade Reagent (Invitrogen), and examined under a fluorescence microscope.Processing of Ear Skin and Lymph Nodes for ex vivo Stimulation and Flow CytometryInjected ears were isolated and minced. Ear skin was then digested for 1 hour at 37uC in 5 mL HBSS containing 1 mg/mL collagenase D (Sigma). Cells were then filtered through 70 mm nylon mesh and washed in complete RPMI before stimulation. Lymph nodes were disrupted using a 1 mL syringe plunger in complete RPMI. Recovered leukocytes were passed through wire mesh to obtain single cell suspensions. Samples were counted using a hemacytometer.Tubastatin-A site Intracellular StainingIntracellular cytokine staining for IL-4 was performed after in vitro activation with PMA (50 ng/mL) and ionomycin (500 ng/ mL) for five hours at 37uC. GolgiPlug (BD Biosciences) was added for the last four hours of stimulation. After stimulation, cells were incubated with Fc block (Biolegend) and stained with antibodies directed against CD3 and CD4. Cells were then fixed and permeabilized using Fix and Perm cell fixation and permeabilization kit (Invitrogen) and stained with antibody against IL-4.Materials and Methods MiceCCR22/2 mi.Ion [34], inflammation [28,35], and graft rejection [36] have demonstrated that CCR2-deficient (CCR22/2) mice exhibit enhanced Th2-type responses with increased production of IL-4 and IL-5, but decreased production of IFN-c. Given this bias toward Th2 immunity in the absence of CCR2 signaling, and a potential role for CCR2 in the pathogenesis of psoriasis, we sought to examine whether CCR2-deficient mice are resistant to the development of IL-23-induced psoriasis. To test the hypothesis that CCR2 is required for the development of psoriasis, we injected WT and CCR22/2 mice intradermally with IL-23. We found that the skin of CCR22/2 mice actually becomes more inflamed than that of WT mice, with increased ear swelling and epidermal thickening. Further, instead of psoriasis-like inflammation seen in WT mice, IL-23-induced cutaneous inflammation in CCR22/2 mice resembled atopic dermatitis. This inflammation was associated with an increased Th2-type immune response. Although comparable numbers of IL4-secreting CD4+ T cells were present in the draining lymph node and inflamed skin of WT and CCR22/2 mice, increased numbers of eosinophils, mast cells and increased expression of IL-4 and TSLP were detected within IL-23 injected CCR22/2 skin.among total leukocytes. 5 mm sections were stained with toluidine blue for mast cell quantitation. Epidermal thickness was evaluated using NIS-Elements software, and was calculated as: the area of the epidermis/the length of the epidermis.Fluorescence ImmunohistologyFluorescence immunohistology was performed on 10 mm frozen ear skin sections. The sections were air dried for 10 minutes, fixed in 4 paraformaldehyde for 8 minutes, and blocked with PBS containing 5 FBS and 2 mg anti-CD16/CD32 (Biolegend) for 30 minutes at room temperature. Sections were then washed twice in PBS 0.1 Tween and stained overnight with 1 mg of an affinity purified polyclonal antibody to mouse TSLP (R D Systems, BAF555) diluted in PBS 0.1 saponin at 4uC. After washing with PBS 0.1 Tween on ice, sections were stained with 1 mg of AlexaFluor 488-conjugated donkey anti-goat IgG (Invitrogen) for 1 hour at room temperature. After again washing with PBS 0.1 Tween, sections were then stained with 1 mg/mL Hoescht in PBS for 5 minutes. Finally, sections were washed in PBS, mounted with ProLong Gold Antifade Reagent (Invitrogen), and examined under a fluorescence microscope.Processing of Ear Skin and Lymph Nodes for ex vivo Stimulation and Flow CytometryInjected ears were isolated and minced. Ear skin was then digested for 1 hour at 37uC in 5 mL HBSS containing 1 mg/mL collagenase D (Sigma). Cells were then filtered through 70 mm nylon mesh and washed in complete RPMI before stimulation. Lymph nodes were disrupted using a 1 mL syringe plunger in complete RPMI. Recovered leukocytes were passed through wire mesh to obtain single cell suspensions. Samples were counted using a hemacytometer.Intracellular StainingIntracellular cytokine staining for IL-4 was performed after in vitro activation with PMA (50 ng/mL) and ionomycin (500 ng/ mL) for five hours at 37uC. GolgiPlug (BD Biosciences) was added for the last four hours of stimulation. After stimulation, cells were incubated with Fc block (Biolegend) and stained with antibodies directed against CD3 and CD4. Cells were then fixed and permeabilized using Fix and Perm cell fixation and permeabilization kit (Invitrogen) and stained with antibody against IL-4.Materials and Methods MiceCCR22/2 mi.